Serum uric acid and anti-N-methyl-d-aspartate receptor encephalitis

•Serum UA levels in patients with anti-NMDAR encephalitis are reduced during attacks.•Treatment normalizes serum UA levels in anti-NMDAR encephalitis.•Patients with mRS scores <4 have higher serum UA levels than those with scores ≥4.•Patients with favourable rather than limited outcomes have higher serum UA levels.•Serum UA levels are significantly associated with mRS scores.

BackgroundUric acid (UA) levels are associated with autoimmune and neurodegenerative disorders, but their relationship with anti-N-methyl-d-aspartate receptor (anti-NMDAR) encephalitis is unknown.MethodsUA levels were evaluated in 58 patients with anti-NMDAR encephalitis, and 58 age- and sex-matched healthy controls (CTLs). Follow-up evaluations of 30 out of the 58 patients with anti-NMDAR encephalitis were conducted 3 months after admission. Modified Rankin scale (mRS) scores and clinical and cerebrospinal fluid parameters were evaluated in all anti-NMDAR encephalitis patients.ResultsSerum UA levels were significantly lower in patients with anti-NMDAR encephalitis than those in CTLs (p < 0.001), and this was especially evident in patients with severe impairments (mRS ≥ 4 vs. <4, p = 0.004) or with limited response to treatment (vs. favourable outcome, p = 0.002). Follow-up evaluations revealed that serum UA levels normalized after treatment, with significantly increased serum UA levels (p < 0.001), and that mRS scores were significantly lower (p < 0.001) than those before treatment. In addition, serum UA levels were significantly associated with mRS scores (r = −0.463, p < 0.001).ConclusionOur results showed that serum UA levels in patients with anti-NMDAR encephalitis are reduced during attacks compared with those in CTLs, are normalized after treatment, and are associated with disease severity.